This invention relates to a soap stick launcher and method for launching soap sticks into gas, oil or other types of wells. More particularly, the present invention relates to the reduction of hydrostatic pressure caused by salt water migrating into well bores.
The presence of water in oil and gas formations is problematic, especially if water migrates into the production tubing. When the hydrostatic pressure of the water column within a well bore overcomes the pressure of the formation fluids, production flow ceases. To counteract the hydrostatic pressure, surfactants in the form of soap sticks are periodically released into the well bore. The surfactants foam the water thereby reducing the hydrostatic pressure so that production from the formation can continue to flow again. Initially, soap sticks were dropped by hand into the well tubing. Methods or apparatus for automatically dropping soap sticks into oil and gas wells at periodic intervals have been used. Gonzalez, in U.S. Pat. No. 6,056,058, teaches a method and apparatus for automatically launching sticks of various materials into oil and gas wells. The apparatus has an enclosed magazine with several chambers containing soap sticks to be released into a well. The magazine is rotated by a double acting cylinder actuator in response to pressure alterations. A pneumatic ratchet means automatically rotates the shaft when a double acting cylinder actuator causes a rod to extend or retract. A solenoid alternates the pressure in response to a signal from a battery operated timer means, an automatic telephone dialing code, a low differential pressure, a low static pressure or changes in flow rate. The ""058 device positions the ratchet means on top of the magazine housing. The ""058 reference also teaches the use of a pressure equalizing line that bypasses the lower manual valve.
Harrison, U.S. Pat. No. 6,044,905, discloses a chemical stick storage and delivery system that utilizes a stacked dual valve system for allowing the chemical sticks to enter into the well bore. A battery-operated timer controls the operation of the stacked first and second valves. A rotatable chemical stick storage device is supported on top of a delivery tube. In one embodiment, when the first valve is opened, a chemical stick drops into a chamber, and when the second valve is opened, the stick drops from the chamber to the well. Both valves are slightly opened at the same time thereby allowing well gases or fluids to enter the stick storage chamber.
The Noyes U.S. Pat. No. 5,188,178, teaches a method and apparatus for automatic well stimulation that has a sequentially actuated magazine to allow a chemical stimulant to be dispense into the well. The ""178 device uses a cylinder-type magazine mounted within an upper chamber to house the sticks within eight cylinders and a motor means to rotate the magazine. Pratt ""455 discloses a chemical dispensing system and method for automatically dispensing chemical sticks into a well bore. The apparatus is a tubular receptacle with an upper storage section and a lower receiving chamber with sticks stacked end to end. The holding device and the receptacle valve are actuated by an actuating mechanism which includes a pneumatic solenoid valve. The valve regulates the flow of gas to a pneumatic cylinder for the holding device and a pneumatic cylinder which is part of the valve actuator for the bottom receptacle valve.
Soap sticks often disintegrate and melt while being stored in the magazine of automatic stick release devices. Moisture in well fluids that rise and fill the magazine disintegrates the soap sticks. Atmospheric heat conditions surrounding well sites can melt the soap. None of the above references adequately solve the problem of disintegration of soap sticks stored in their automatic stick release devices.
The present invention provides a stick launcher for launching soap sticks into a gas or oil well. The soap stick launcher and method of this invention avoids contamination from moisture present in the well bore by maintaining the storage container in a state of overpressure. The preferred soap stick launcher also uses a quick action ball valve system to reduce exposure of the soap sticks to moisture laden fluids from the well bore. Heat deterioration of the soap sticks is avoided by a cooling system which maintains the temperatures of the storage container approximately 10xc2x0 F. to 60xc2x0 F. below ambient temperatures. One preferred embodiment of the stick launcher comprises a compact containment vessel that is adapted to house soap sticks of various sizes and shapes. The containment vessel has a contiguous wall and a top and a bottom. The vessel further comprises a removable and sealable top plate and a bottom plate defining an opening. A turret-style separator sits within the containment vessel. This separator is constructed from a series of faceted blades that interlock to define a quill shape internal diameter and project a separation blade radially outward. The separator can be removable and rotatable. The separator is adapted to contain the soap sticks between the blades of the separator and the contiguous wall of the containment vessel. Because bulky cylinders are not required for each soap stick, the containment vessel can be compact and light weight.
Soap sticks tend to react with water, especially salt water. It is important that moisture-containing well fluids, gaseous or liquid, have minimal contact with the soap sticks. A ball valve is positioned adjacent the bottom of the containment vessel. The ball valve, when in open position, is adapted to be in fluid communication with a well bore and the containment vessel. Preferably, the bottom plate comprises a threaded connector. The opening in the bottom plate and the threaded connector define a passageway for the soap stick so that rotating the turret styled separator positions a soap stick immediately above the ball valve.
A rotating assembly, when set in motion by an actuator, is used to rotate the separator and simultaneously open or close the ball valve. Preferably, the rotating assembly comprises a ratchet mechanism and an actuator plate that, while acting on the separator to advance a soap stick into position in the passage way, opens and closes the ball valve so that the containment vessel, and the soap sticks within it, have minimal contact with the moisture laden fluids of the well bore.
Preferably, the ratchet mechanism comprises a pawl body, two or more pawls mounted on the pawl body, a ratchet arm and an actuator plate. The actuator plate is connected to the ball valve. The actuator plate is joined to the ratchet arm by a linkage. The pawl body comprises an upper section, a lower section and a middle section. The upper section and middle section are within the containment vessel and the lower section extends outside of the bottom plate. The pawls can be mounted on the upper section of the pawl body for engaging with and rotating the blades of the turret-style separator. The ratchet arm is mounted radially to the axis of the containment vessel for engagement with the lower section of the pawl body, so that rotation of the actuator plate opens the ball valve and moves the ratchet arm in a direction so as to disengage the pawls from the blades of the turret styled separator. In this way, a soap stick in the passage way drops through the ball valve into the well bore. Simultaneously, the disengagement of the pawls from the blades prevents rotation of the separator. Immediately after the soap stick drops through the ball valve, the actuator rotates the ratchet arm in an opposite direction to close off the ball valve and simultaneously advance another soap stick into the passage way.
In one embodiment, the actuator for rotating the rotating assembly is a gas cylinder mounted adjacent the containment vessel. Preferably, the gas cylinder is linked to the actuator plate for rotating the rotating assembly. In one preferred embodiment, the actuator plate comprises a first end, a second end and a middle, the first end attached to the ratchet arm, the middle attached to the ball valve and the second end linked to the gas cylinder. Preferably, the stick launcher further comprises an electronic controller for extending and retracting the gas cylinder so that extending the gas cylinder rotates the actuator plate in a first direction to open the ball valve and to simultaneously move the linkage connected to the ratchet arm so that the pawls disengage the blades of the separator. Retracting the gas cylinder rotates the actuator plate in an opposing direction to close the ball valve and simultaneously move the linkage connected to the ratchet arm so that blades of the separator re-engage the pawls to rotate the separator and advance another soap stick to the passage way above the ball valve.
In a preferred method for launching soap sticks into a gas or oil well, the method comprises:
a) loading soap sticks into a stick launcher comprising a containment vessel, a rotating assembly connected to an actuator for rotating the rotating assembly and a ball valve in fluid communication with a well bore. Preferably, the ball valve is joined to the rotating assembly. The containment vessel can have a removable top, a contiguous wall and a separator with blades, the blades in a clearance position relative to the contiguous wall so that the blades and the contiguous wall define a plurality of compartments;
b) positioning the soap sticks within the compartments. The bottom of the containment vessel defines an opening above the ball valve;
c) rotating the separator using the actuator and rotating assembly to rotate the separator in a first direction to advance a soap stick above the opening so that one stick falls through the opening and comes to rest on top of the ball valve;
d) closing the ball valve simultaneously to the rotation in step (c) by rotating the ball valve with the rotating assembly of step (c) to avoid well fluids from entering the containment vessel;
e) rotating the ball valve in a direction opposite to the first direction of step (c) to open the ball valve so that the soap stick drops into the well bore, while simultaneously disengaging the rotating mechanism from the separator to prevent the separator from rotating while the soap stick is dropping;
f) maintaining the containment vessel in an overpressure condition so that pressure from the containment vessel is exhausted while the ball valve is opened to avoid the inhalation of well fluids into the containment vessel.
In another preferred embodiment, the stick launcher for launching soap sticks comprises a cooling system to keep the containment vessel 10xc2x0 F. to about 60xc2x0 F. below ambient temperatures thereby further reducing the deterioration of the soap sticks.